Nylon Linear Bearings and shafting

[Jcadwell]

Has anybody tried using Nylon Linear Plain Bearings for a router table or anything like it? McMaster has 3/4" ID bearings for 5.69$. Not bad compared to linear ball bearings.

The shafting isn't way out of line either. The hardened precision stuff is 46.38$ for 48", and the generic bar is 29.44$ for chrome plated or 33.00$ for nitride coating.

Any merit in running a real hardened or precision shaft?

[hook'em]

Jcadwell - just a note to you when looking for precision shaft - try Reid Tool Supply Co. (reidtool.com). I just bought the same 3/4" 48" shaft for $32. and change. Reid beat McMaster, MSC and Enco for Thomson 60 case harsened shaft. I also got the pacific plain frelon lined bearings for about the same as all the others. I might be a little leary of the nylon plain bearings due to tolerancing and potential thermal expansion. But if they fit and are close enough for you, they sound like a great bargain.

[Jcadwell]

I've never seen a machine with them? Most people seem to go the rollerblade bearing route for cheap machines. Doesn't seem much cheaper, and it is quite a bit more complicated to build all the bearing fixtures.

[hook'em]

I'll let you know if it's easy after I've made them all. So far I've made four "pillow blocks" and it was pretty easy. I took some mdf (3/4" thk) and made several 2" x 2" squares. It takes 3 to make on block. The center one is drilled thru the 3/4" thickness while the end ones are counterbored and drilled (counterbored to fit the bearing and drilled for shaft clearance). The bearing is placed inside of the 3 pcs, then glue the blocks together. I haven't decided on how I am going to mount them to the table (axis) but I'm pretty set on some aluminum angle along each side of the "bearing block". It all works in my head, but ...

[hook'em]

OOOPS. I thought you were refering to the frelon lined being 'not cheaper', sorry. But anyway, what I described might be a cheaper way to get pillow blocks.

[Jcadwell]

Your pillow block model is exactly what I was thinking. The rollerblade bearings take lots of them to make a single axis work. If the bearings are 1$ each you get close to the price of 12 nylon sleeves in not much time at all. And I think sleeves on some real drill rod or shaft would be more rigid, though I may be wrong. At least it is a fully captive system.

The frelons are definately more expensive than either nylon or rollerblade bearings. I'm just thinking for not much more than rollerblade bearings you might be able to build a better system with nylon. The rod does get spendy though...

[vacpress]

consider rollerblade bearings on square steel tube held at an angle so its like a diamond. you can get away with 8 ball bearings per axis that way. think shopbot, but isntead of angle iron, steel square tube..

[doug6949]

You can make your own "frelon" bearings by pouring Moglice or its homemade equivalent into MDF or aluminum blocks. The blocks, table and rails are all assembled first and the casting is done in place.

DIY Moglice is just a mixture of epoxy, moly disulfide and teflon powder. The rails can be CRS round or square, anodized aluminum or Thomson shaft if you are rich. The nice thing about this method is that the blocks can be made with a saw and drill because alignment is not critical. You just have to get the rails parallel and the table assembly positioned correctly before you pour. Don't forget to use release agent on the rails.

Doug